Earlier this week I discussed the possibility of a stronger cold front making its way in by the middle of next week. Since that discussion, Tropical Storm Nate has developed in the Gulf of Mexico, which will have a big impact on the upcoming weather. I wrote a fairly detailed discussion on how tropical storms impact the overall weather pattern in a previous post. You can find that discussion here if you want to learn more. In a nutshell, the aforementioned front will not impact nearly as many areas as previously forecasted. Tropical storms are very difficult to forecast, which, if you watch any tropical storm coverage you are probably aware of this. For this reason I don’t like to talk much about them until I know for sure they will affect the forecast. Now that we know it will, let’s discuss briefly what to expect for the next several days as Nate approaches and moves through.

At the time of this writing TS Nate is deep in the Gulf of Mexico, expected to become a Hurricane fairly soon. I won’t discuss the details of Nate, if you would like to read more you can visit the National Hurricane Center here. As Nate approaches it will begin to create a “block” in the jet stream, which will put a damper on the low pressure system that was expected to bring the strong cold front south. The following loop of the NAM model shows this:

Notice how as Nate approaches it pushes the jet stream northward. This is the “blocking” effect, and as a result a ridge builds over the eastern half of the US and the trough that comes in behind Nate takes a more northerly track. This will result in higher temperatures across this area. If we look at a loop of the same time frame of surface temperatures we can see how the cold front to the northwest struggles to move southeast. It gets sort of L-shaped as it reaches Oklahoma and Kansas:

It looks like folks in the plains could still see a pretty decent cold front but it may be some time before the eastern US gets a strong push from the north. This is the full run of the NAM but longer range models show the cold front mixing out shortly after this time. I will discuss more in Monday’s forecast discussion.